A cave automatic virtual environment (CAVE) projection system is a large virtual reality (VR) system, with high degrees of immersion and interactivity. The CAVE projection system can fuse vision, touch, sound and other senses, and can track head movement along 6 degrees of freedom. The principles of a CAVE immersive virtual reality display system are relatively complex. It is based on computer graphics, and perfectly fuses the high-resolution three-dimensional projection display technology, multi-channel visual synchronization technology, three-dimensional computer graphics technology, audio technology, sensor technology and so on. The CAVE immersive virtual reality display system is therefore able to produce a completely immersive virtual environment surrounded by a three-dimensional projection image sand can be used by multiple people. At present, real-time high-resolution multi-window content rendering of a complex scene is mainly applied to the CAVE system. The CAVE projection system is a large VR system with high degree of immersion and interactivity. The CAVE projection system is a highly immersive virtual demonstration environment composed three or more (i.e. including three) hard rear-projection walls. An observer is surrounded by the virtual reality system with a plurality of images, and a plurality of projection surfaces form a virtual space. The common CAVE system projection space is a standard cubic structure, and the four independent projection channels finally form a space continuous projection image.
As shown in FIG. 1, the CAVE system includes a projection array and a visual platform. The projection array includes a plurality of optical machines 6-10, and the visual platform includes a plurality of visual planes 1-5. The visual plane is a projection screen. In an example of the CAVE system, the projection array includes five optical machines, and the five optical machines are arranged in a pentagonal shape. The visual planes include four horizontal visual projection screens 1-4 and one bottom visual projection screen 5, and the five optical machines are projected to five planes of the visual planes, respectively. Five optical machines are connected with a data host to form a projection image, respectively, and the user 11 stands on the bottom visual projection screen 5 during the usage. A sight line of the user in the present invention generally only aims at the horizontal visual projection screens 1-4.
At present, the interior of a common optical machine has only one set of optical engines which are equipped with one lens. Limited by Texas Instruments DLP technology, at present, the highest resolution output of a single optical machine is 4 k (i.e., resolution is 3840×2160), and the price is quite high. Since the optical machine with 4K output has just come out, it belongs to a test stage. There is not a plurality of selected types for the throw ratio, that is, there is not a plurality of focal length lenses to choose. If ultra-high resolution output with a resolution of more than 4K needs to be achieved, a plurality of single optical machines should be subjected to hardware fusion or software fusion. However, drawbacks of the fusion way of the projection equipment in the prior art are as follows, firstly, the resolution outputted by a single set of optical engine equipped by the single optical machine is limited. For example, the resolutions of the common optical machines on the market is 1080*720 and 1920×1080. The resolution of some single high-end optical machines can achieve 4K (3840×2160), while the price is high. Currently, there is no single optical machine on the market which achieves four screen output with 4K. Secondly, mutual fusion between a plurality of single optical machines is performed, which cannot be commercialized and industrialized at all. Moreover, each of the optical machines is an independent structure, resulting in changes in the relative position between the optical machines after a long time, which directly affects the splicing and fusion of the image. Thirdly, for the optical machines with the same parameters, the hardware difficulty and the price of the optical machines with short focal length are higher than those of the normal focal length.